cherry-pick: refuse cherry-pick sequence if index is dirty

Cherry-pick, like merge or rebase, refuses to run when there are changes
in the index. However, if a cherry-pick sequence is requested, this
refusal happens "too late": when the cherry-pick sequence has already
started, and an "--abort" or "--quit" is needed to resume normal
operation.

Normally, when an operation is "in-progress" and you want to go back to
where you were before, "--abort" is the right thing to run. If you run
"git cherry-pick --abort" in this specific situation, however, your
staged changes are destroyed as part of the abort! Generally speaking,
the abort process assumes any changes in the index are part of the
operation to be aborted.

Add an earlier check in the cherry-pick sequence process to ensure that
the index is clean, introducing a new general "quit if index dirty" function
derived from the existing worktree-level function used in rebase and pull.
Also add a test.

Signed-off-by: Tao Klerks <tao@klerks.biz>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

sequencer.c

@@ -3162,38 +3162,48 @@ static int walk_revs_populate_todo(struct todo_list *todo_list,
 	return 0;
 }
 
-static int create_seq_dir(struct repository *r)
+static const char *cherry_pick_action_name(enum replay_action action) {
+	switch (action) {
+	case REPLAY_REVERT:
+		return "revert";
+		break;
+	case REPLAY_PICK:
+		return "cherry-pick";
+		break;
+	default:
+		BUG("unexpected action in cherry_pick_action_name");
+	}
+}
+
+static int create_seq_dir(struct repository *r, enum replay_action requested_action)
 {
-	enum replay_action action;
+	enum replay_action in_progress_action;
+	const char *in_progress_action_name = NULL;
 	const char *in_progress_error = NULL;
 	const char *in_progress_advice = NULL;
+	const char *requested_action_name = NULL;
 	unsigned int advise_skip =
 		refs_ref_exists(get_main_ref_store(r), "REVERT_HEAD") ||
 		refs_ref_exists(get_main_ref_store(r), "CHERRY_PICK_HEAD");
 
-	if (!sequencer_get_last_command(r, &action)) {
+	if (!sequencer_get_last_command(r, &in_progress_action)) {
-		switch (action) {
+		in_progress_action_name = cherry_pick_action_name(in_progress_action);
-		case REPLAY_REVERT:
+		in_progress_error = _("%s is already in progress");
-			in_progress_error = _("revert is already in progress");
 		in_progress_advice =
-			_("try \"git revert (--continue | %s--abort | --quit)\"");
+		_("try \"git %s (--continue | %s--abort | --quit)\"");
-			break;
-		case REPLAY_PICK:
-			in_progress_error = _("cherry-pick is already in progress");
-			in_progress_advice =
-			_("try \"git cherry-pick (--continue | %s--abort | --quit)\"");
-			break;
-		default:
-			BUG("unexpected action in create_seq_dir");
-		}
 	}
 	if (in_progress_error) {
-		error("%s", in_progress_error);
+		error(in_progress_error, in_progress_action_name);
 		if (advice_enabled(ADVICE_SEQUENCER_IN_USE))
 			advise(in_progress_advice,
+				in_progress_action_name,
 				advise_skip ? "--skip | " : "");
 		return -1;
 	}
+	requested_action_name = cherry_pick_action_name(requested_action);
+	if (require_clean_index(r, requested_action_name,
+				    _("Please commit or stash them."), 1, 1))
+		return -1;
 	if (mkdir(git_path_seq_dir(), 0777) < 0)
 		return error_errno(_("could not create sequencer directory '%s'"),
 				   git_path_seq_dir());
@@ -5223,12 +5233,11 @@ int sequencer_pick_revisions(struct repository *r,
 
 	/*
 	 * Start a new cherry-pick/ revert sequence; but
-	 * first, make sure that an existing one isn't in
+	 * first, make sure that the index is clean and that
-	 * progress
+	 * an existing one isn't in progress.
 	 */
-
 	if (walk_revs_populate_todo(&todo_list, opts) ||
-			create_seq_dir(r) < 0)
+			create_seq_dir(r, opts->action) < 0)
 		return -1;
 	if (repo_get_oid(r, "HEAD", &oid) && (opts->action == REPLAY_REVERT))
 		return error(_("can't revert as initial commit"));

t/t3510-cherry-pick-sequence.sh

@@ -47,6 +47,16 @@ test_expect_success 'cherry-pick persists data on failure' '
 	test_path_is_file .git/sequencer/opts
 '
 
+test_expect_success 'cherry-pick sequence refuses to run on dirty index' '
+	pristine_detach initial &&
+	touch localindexchange &&
+	git add localindexchange &&
+	echo picking &&
+	test_must_fail git cherry-pick initial..picked &&
+	test_path_is_missing .git/sequencer &&
+	test_must_fail git cherry-pick --abort
+'
+
 test_expect_success 'cherry-pick mid-cherry-pick-sequence' '
 	pristine_detach initial &&
 	test_must_fail git cherry-pick base..anotherpick &&

wt-status.c

@@ -2616,14 +2616,11 @@ int has_uncommitted_changes(struct repository *r,
 	return result;
 }
 
-/**
+static int require_clean_index_or_work_tree(struct repository *r,
- * If the work tree has unstaged or uncommitted changes, dies with the
- * appropriate message.
- */
-int require_clean_work_tree(struct repository *r,
 				     const char *action,
 				     const char *hint,
 				     int ignore_submodules,
+				     int check_index_only,
 				     int gently)
 {
 	struct lock_file lock_file = LOCK_INIT;
@@ -2635,11 +2632,13 @@ int require_clean_work_tree(struct repository *r,
 		repo_update_index_if_able(r, &lock_file);
 	rollback_lock_file(&lock_file);
 
+	if (!check_index_only) {
 		if (has_unstaged_changes(r, ignore_submodules)) {
 			/* TRANSLATORS: the action is e.g. "pull with rebase" */
 			error(_("cannot %s: You have unstaged changes."), _(action));
 			err = 1;
 		}
+	}
 
 	if (has_uncommitted_changes(r, ignore_submodules)) {
 		if (err)
@@ -2659,3 +2658,39 @@ int require_clean_work_tree(struct repository *r,
 
 	return err;
 }
+
+/**
+ * If the work tree has unstaged or uncommitted changes, dies with the
+ * appropriate message.
+ */
+int require_clean_work_tree(struct repository *r,
+			    const char *action,
+			    const char *hint,
+			    int ignore_submodules,
+			    int gently)
+{
+	return require_clean_index_or_work_tree(r,
+						action,
+						hint,
+						ignore_submodules,
+						0,
+						gently);
+}
+
+/**
+ * If the work tree has uncommitted changes, dies with the appropriate
+ * message.
+ */
+int require_clean_index(struct repository *r,
+			const char *action,
+			const char *hint,
+			int ignore_submodules,
+			int gently)
+{
+	return require_clean_index_or_work_tree(r,
+						action,
+						hint,
+						ignore_submodules,
+						1,
+						gently);
+}

wt-status.h

@@ -181,5 +181,10 @@ int require_clean_work_tree(struct repository *repo,
 			    const char *hint,
 			    int ignore_submodules,
 			    int gently);
+int require_clean_index(struct repository *repo,
+			    const char *action,
+			    const char *hint,
+			    int ignore_submodules,
+			    int gently);
 
 #endif /* STATUS_H */